John Treadwell graduated from Yale University and studied law, subsequently practicing in Farmington. He held various judicial and legislative positions, including serving on the governor's council and as a member of the General Assembly. Treadwell transitioned from private practice to public service, holding roles such as Judge of the Court of Common Pleas and delegate to the state convention that ratified the US Constitution. He was elected to multiple terms as Lieutenant Governor and later assumed the governorship of Connecticut. Throughout his career, Treadwell demonstrated leadership in both the legal and political spheres.

John Treadwell's political career reveals a nuanced blend of regionalism and ideological flexibility. His support for the Non-Intercourse Act during his governorship illustrates a calculated effort to safeguard local economic interests against national conflict. Treadwell's participation in the Hartford Convention underscores a strategic engagement with broader constitutional debates, balancing local grievances with national governance. His founding of the Connecticut Missionary Society indicates a commitment to religious outreach that aligns with broader Congregationalist objectives.